2024 multidisciplinary consensus on image-guided lung tumor ablation from the Taiwan Academy of Tumor Ablation.

In this article, the multidisciplinary team of the Taiwan Academy of Tumor Ablation, who have expertise in treating lung cancer, present their perspectives on percutaneous image-guided thermal ablation (IGTA) of lung tumors. The modified Delphi technique was applied to reach a consensus on clinical practice guidelines concerning ablation procedures, including a comprehensive literature review, selection of panelists, creation of a rating form and survey, and arrangement of an in-person meeting where panelists agreed or disagreed on various points. The conclusion was a final rating and written summary of the agreement. The multidisciplinary expert team agreed on 10 recommendations for the use of IGTA in the lungs. These recommendations include terms and definitions, line of treatment planning, modality, facility rooms, patient anesthesia settings, indications, margin determination, post-ablation image surveillance, qualified centers, and complication ranges. In summary, IGTA is a safe and feasible approach for treating primary and metastatic lung tumors, with a relatively low complication rate. However, decisions regarding the ablation technique should consider each patient's specific tumor characteristics.

Thromboprophylaxis in varicose veins surgery: The everyday concern.

Venous thromboembolic disease (VTE) occupies an important place as a cause of morbidity and mortality in surgical patients in all specialties. Despite the existence of guidelines for thrombo prophylaxis in surgery, it is not clear due to the lack of current evidence, how to develop antithrombotic prophylaxis in varicose vein surgery and many questions arise when the surgeon is faced with a patient to be operated on. A comprehensive review of the literature was conducted to examine the evidence about the prevention of the venous thromboembolism in varicose veins surgery patients, and aims to guide the reader through questions that arise in daily practice, discussing the different scenarios presented in the literature for the choice of the most appropriate prophylaxis for each case. The lack of conclusive literature determines that risk should be individualized using available scales and other procedure-related factors, so that the type and duration of prophylaxis can be determined on a case-by-case basis.

Comparison of two ablation procedures combined with high ligation and foam sclerotherapy and compression therapy for patients with venous leg ulcers.

AIM: To compare the ablation techniques' efficacy of endovenous microwave ablation (EMA) combined with high ligation (HL), foam sclerotherapy (FS) and compression therapy (CT) and endovenous laser ablation (EVLA) combined with HL-FS-CT in the treatment of VLUs. METHOD: 301 consecutive patients with VLUs from 2013 to 2022 in a 3200-bed hospital were intervened by EMA combined with HL-FS-CT and EVLA combined with HL-FS-CT were retrospectively compared. RESULTS: One hundred thirty-four patients underwent EMA+HL-FS-CT and 167 patients underwent EVLA+HL-FS-CT. The primary outcome of the ulcer healing time was 1.45(0.75-1.5) months and 1.86(0.5-2.5) months, respectively, in the two groups (HR for ulcer healing was 1.26, 95% CI [0.96-1.66], p = 0.097). Secondary outcomes included that no significant difference was found in ulcer recurrence and GSV recanalization and complications between the two groups, and the postoperative VCSS and AVVQ were significantly lower than the baseline values in the respective groups (p = 0.0001). CONCLUSION: EMA+HL-FS-CT and EVLA+HL-FS-CT are both effective at treating VLUs. Both of the two comprehensive treatments were beneficial to the healing of ulcers, but no evidence showed which one was superior in the ulcer healing time.

Image Guided Energy Ablation for Palliation of Painful Bony Metastases - A Systematic Review.

PURPOSE: To analyze the effectiveness of image-guided energy ablation techniques with and without concurrent therapies in providing palliative pain relief in patients with bone metastases. MATERIALS AND METHODS: OVID Embase, OVID Medline, and Pubmed were searched from inception to April 14th, 2023 using search terms relating to bone lesions and MeSH terms regarding ablation therapy. English peer-reviewed primary articles were included that reported pain scores following image-guided energy-based ablation of bone metastases. Exclusion criteria included 1) non-palliative treatment, 2) pain scores associated with specific treatment modalities not reported, and 3) non-metastatic bone lesions. Mean percentage reduction in pain score was calculated. RESULTS: 1396 studies were screened and 54 were included. All but one study demonstrated decreased pain scores at final follow-up. Mean reduction in pain scores at final follow-up were 49% for radiofrequency ablation (RFA), 58% for radiofrequency ablation and adjunct (RFA-A), 54% for cryoablation (CA), 72% for cryoablation and adjunct (CA-A), 48% for microwave ablation (MWA), 81% for microwave ablation and adjunct (MWA-A), and 64% for high-intensity focused ultrasound (HIFU). Post-procedural adverse event rates were 4.9% for RFA, 34.8% for RFA-A, 9.6% for CA, 12.0% for CA-A, 48.9% for MWA, 33.5% for MWA-A and 17.0% for HIFU. CONCLUSION: Image-guided energy ablation demonstrated consistently strong reduction in pain across all modalities, with variable post-procedural adverse event rates. Due to heterogeneity of included studies, quantitative analysis was not appropriate. Future primary research should focus on creating consistent prospective studies with established statistical power, explicit documentation and comparison to other techniques.

Application of Deep Learning for Real-Time Ablation Zone Measurement in Ultrasound Imaging.

BACKGROUND: The accurate delineation of ablation zones (AZs) is crucial for assessing radiofrequency ablation (RFA) therapy's efficacy. Manual measurement, the current standard, is subject to variability and potential inaccuracies. AIM: This study aims to assess the effectiveness of Artificial Intelligence (AI) in automating AZ measurements in ultrasound images and compare its accuracy with manual measurements in ultrasound images. METHODS: An in vitro study was conducted using chicken breast and liver samples subjected to bipolar RFA. Ultrasound images were captured every 15 s, with the AI model Mask2Former trained for AZ segmentation. The measurements were compared across all methods, focusing on short-axis (SA) metrics. RESULTS: We performed 308 RFA procedures, generating 7275 ultrasound images across liver and chicken breast tissues. Manual and AI measurement comparisons for ablation zone diameters revealed no significant differences, with correlation coefficients exceeding 0.96 in both tissues (p < 0.001). Bland-Altman plots and a Deming regression analysis demonstrated a very close alignment between AI predictions and manual measurements, with the average difference between the two methods being -0.259 and -0.243 mm, for bovine liver and chicken breast tissue, respectively. CONCLUSION: The study validates the Mask2Former model as a promising tool for automating AZ measurement in RFA research, offering a significant step towards reducing manual measurement variability.

Advances in Tumor Management: Harnessing the Potential of Histotripsy.

Tissue ablation techniques have long been used in clinical settings to treat various oncologic diseases. However, many of these techniques are invasive and can cause substantial adverse effects. Histotripsy is a noninvasive, nonionizing, nonthermal tissue ablation technique that has the potential to replace surgical interventions in various clinical settings. Histotripsy works by delivering high-intensity focused ultrasound waves to target tissue. These waves create cavitation bubbles within tissues that rapidly expand and collapse, thereby mechanically fractionating the tissue into acellular debris that is subsequently absorbed by the body's immune system. Preclinical and clinical studies have demonstrated the efficacy of histotripsy in treating a range of diseases, including liver, pancreatic, renal, and prostate tumors. Safety outcomes of histotripsy have been generally favorable, with minimal adverse effects reported. However, further studies are needed to optimize the technique and understand its long-term effects. This review aims to discuss the importance of histotripsy as a noninvasive tissue ablation technique, the preclinical and clinical literature on histotripsy and its safety, and the potential applications of histotripsy in clinical practice. Keywords: Tumor Microenvironment, Ultrasound-High-Intensity Focused (HIFU), Ablation Techniques, Abdomen/GI, Genital/Reproductive, Nonthermal Tissue Ablation, Histotripsy, Clinical Trials, Preclinical Applications, Focused Ultrasound © RSNA, 2024.

Endotracheal enucleation and para-toluenesulfonamide injection for adenoid cystic carcinoma in the upper trachea: A novel therapeutic approach.

We present a case of an adenoid cystic carcinoma (ACC) located in the upper trachea, which resulted in significant airway blockage, that was unsuitable for surgical removal due to concerns about functional impairment. Instead, endotracheal enucleation via rigid bronchoscopy was performed initially, followed by the injection of a novel tumor ablation agent known as para-toluenesulfonamide (PTS). We detail the dosing regimen, effectiveness evaluation, and post-treatment follow-up. The study highlights the potential of PTS injection as a viable alternative treatment option for patients with ACC who cannot undergo surgical resection and feasibility of lipiodol to monitor treatment effect. This research adds to the existing knowledge on ACC treatment and provides new therapeutic possibilities for patients with tracheal ACC.

Additional local therapy before disease progression for EGFR-mutated advanced lung cancer: a systematic review and meta-analysis.

Background: International guidelines recommend the use of local therapy (LT) to limited progression in patients with epidermal growth factor receptor (EGFR)-mutated advanced non-small cell lung cancer (NSCLC). However, the use of LT before disease progression has not been extensively analyzed. This meta-analysis evaluates the efficacy and safety of administering additional LT in conjunction with first-line EGFR-tyrosine kinase inhibitors (TKIs) before disease progression in patients with EGFR-mutated advanced NSCLC. Methods: We systematically searched PubMed, Embase, and the Cochrane Library for studies published up until May 31, 2023. The LT group consisted of patients who received first-line EGFR-TKIs in conjunction with additional LT, while the TKI group comprised participants treated with first-line EGFR-TKIs alone. Studies comparing the survival outcomes of the LT and TKI groups were included in this analysis. The primary outcomes were progression-free survival (PFS) and overall survival (OS). This review was registered on PROSPERO (registration number CRD42023439913). Results: Among the 11 investigated studies covering 1,313 patients, the LT modalities included radiotherapy, surgery, and ablation therapy, which accounted for 91%, 27%, and 27% of the studies, respectively. The pooled hazard ratios of median PFS and OS were 0.34 [95% confidence interval (CI): 0.22-0.53; P<0.001] and 0.42 (95% CI: 0.36-0.48; P<0.001), respectively, which indicated significant benefits for the LT group compared to the TKI group. There was no significant difference between the LT and TKI groups (P=0.473) regarding the incidence of grade 3 or higher adverse events. Conclusions: This study suggests that the strategic use of additional LT before disease progression is a promising approach for the treatment of EGFR-mutated advanced NSCLC.

Efficacy of microwave ablation in the treatment of large benign thyroid nodules: a multi-center study.

OBJECTIVE: To evaluate the efficacy, safety, and improvement of symptoms by ultrasound-guided microwave ablation (MWA) for patients with large benign thyroid nodules (BTNs). METHODS: Eighty-seven patients with 87 BTNs (≥ 4 cm) treated with MWA between April 2015 and March 2021 were enrolled in this retrospective multicenter study, with clinical and ultrasound examinations performed at the 1st, 3rd, 6th, and 12th months. A multivariable linear mixed effects model was employed to explore the alterations in volume and volume reduction ratio (VRR), as well as the potential factors associated with VRR. RESULTS: The mean age of the 87 patients was 45.69 ± 14.21 years (range 18-76 years), and the ratio of men to women was 1:4.8. The mean volumes were much decreased at the 12th month after ablation compared to the initial volumes (p < .001). The mean VRR was 76.09% at the 12th month. The technique efficacy (VRR > 50%) was 90.80% at the 12th month. A multivariate analysis revealed that VRR was related to the initial volume (p = .015), annular flow (p = .010), and nodule composition (p = .024). The mean symptomatic score decreased from 4.40 ± 0.28 to 0.26 ± 0.06 at the 12th month (p < .001). At the same time, the mean cosmetic score decreased from 3.22 ± 0.10 to 1.31 ± 0.08 (p < .001). CONCLUSION: MWA could serve as a safe and effective therapy for large BTNs, significantly reducing the volume of BTNs and significantly improving compressive symptoms and appearance problems. CLINICAL RELEVANCE STATEMENT: Microwave ablation could serve as a safe and effective therapy for large benign thyroid nodules, leading to significant volume reduction and satisfied symptom and cosmetic alleviation period. KEY POINTS: • This multicenter study investigated the feasibility and safety of microwave ablation for large benign thyroid nodules. • After ablation, the nodule volume was significantly reduced, and patients' symptoms and appearance problems were significantly improved. • Microwave ablation is feasible for large benign thyroid nodules and has been a supplement treatment.

Electroporación irreversible: ampliando las fronteras de la ablación / Irreversible electroporation: Beyond the limits of tumor ablation

La electroporación irreversible o IRE (irreversible electroporation) es una técnica de ablación tumoral no térmica basada en la aplicación de pulsos eléctricos de alto voltaje entre pares de agujas insertadas alrededor de un tumor. La corriente generada favorece la creación de nanoporos en la membrana plasmática, desencadenando la apoptosis. Por ello, la IRE puede utilizarse de manera segura en localizaciones cercanas a estructuras vasculares delicadas, contraindicadas para el resto de técnicas termoablativas. Actualmente la IRE se emplea con éxito para la ablación de tumores en páncreas, riñón e hígado y, de manera muy extendida, como opción terapéutica focal para el cáncer de próstata. La necesidad de un manejo anestésico específico y la colocación precisa y en paralelo de múltiples agujas implican un alto nivel de complejidad, siendo necesaria una gran experiencia del equipo intervencionista. No obstante, se trata de una técnica muy prometedora con una gran capacidad inmunológica sistémica que puede provocar un efecto a distancia del tumor tratado (efecto abscopal).(AU)

Irreversible electroporation (IRE) is a non-thermal tumor ablation technique. High-voltage electrical pulses are applied between pairs of electrodes inserted around and/or inside a tumor. The generated electric current induces the creation of nanopores in the cell membrane, triggering apoptosis. As a result, IRE can be safely used in areas near delicate vascular structures where other thermal ablation methods are contraindicated. Currently, IRE has demonstrated to be a successful ablation technique for pancreatic, renal, and liver tumors and is widely used as a focal therapeutic option for prostate cancer. The need for specific anesthetic management and accurate parallel placement of multiple electrodes entails a high level of complexity and great expertise from the interventional team is required. Nevertheless, IRE is a very promising technique with a remarkable systemic immunological capability and may impact on distant metastases (abscopal effect).(AU)

The relationship between ablation range and ablation energy in papillary thyroid microcarcinoma: a comparison between microwave ablation and laser ablation.

OBJECTIVES: To study the relationship between the ablation range and applied energy of laser ablation (LA) and microwave ablation (MWA) in papillary thyroid microcarcinoma (PTMC). METHODS: A total of 201 PTMC patients were treated with LA (n = 102) or MWA (n = 99) with single-applicator fixed ablation. The ablation range was determined by contrast-enhanced ultrasound. The ratios of ablation volume, longitudinal diameter, and orthogonal diameter to ablation energy (RAV/E, RAL/E, RAO/E) were analyzed and compared between MWA and LA. The effects of PTMC characteristics and Hashimoto's thyroiditis (HT) on ablation efficiency were evaluated by linear regression. RESULTS: The RAV/E was 0.72 (0.65-0.84) mm3/J for MWA and 0.48 (0.39-0.54) mm3/J for LA. HT was significantly correlated with RAV/E of LA (coefficient = - 0.367, p < 0.0001). RAL/E did not differ significantly between MWA and LA (MWA 0.026 mm/J, LA 0.025 mm/J; p = 0.957). However, MWA had a greater RAO/E than LA (MWA 0.014 mm/J, LA 0.012 mm/J; p < 0.0001). The plateau values of MWA and LA on the ablation orthogonal diameter were 10.7 mm and 8.69 mm, respectively. CONCLUSIONS: MWA showed a higher RAV/E than LA. More intuitively, MWA had a better ablation performance than LA on the orthogonal axis rather than the longitudinal axis. Theoretically, MWA and LA could achieve complete ablation of ≤ 6.70 mm and ≤ 4.69 mm PTMC separately by single-applicator fixed ablation considering a unilateral 2-mm safe margin. HT had a negative effect on LA but not on MWA. CLINICAL RELEVANCE STATEMENT: This study establishes strong connections between ablation energy and ablation range in papillary thyroid microcarcinoma (PTMC) in vivo, possibly contributing to the supplementation of the PTMC Ablation Consensus or Guidelines and providing a scientific basis for choosing clinical ablation parameters in PTMC. KEY POINTS: • Both microwave ablation (MWA) and laser ablation (LA) have excellent performance on the ablation longitudinal axis (easily exceeding 10 mm) for papillary thyroid microcarcinoma (PTMC). • MWA performed much better than LA on the ablation orthogonal axis. • MWA and LA are expected to achieve complete ablation of ≤ 6.70 mm and ≤ 4.69 mm PTMC separately by single-applicator fixed ablation considering a unilateral 2-mm safe margin.

Novel and Advanced Ultrasound Techniques for Thyroid Thermal Ablation.

Thyroid radiofrequency ablation and microwave ablation are widely adopted minimally invasive treatments for diverse thyroid conditions worldwide. Fundamental skills such as the trans-isthmic approach and the moving shot technique are crucial for performing thyroid ablation, and advanced techniques, including hydrodissection and vascular ablation, improve safety and efficacy and reduce complications. Given the learning curve associated with ultrasound-guided therapeutic procedures, operators need training and experience. While training models exist, limited attention has been given to ultrasound maneuvers in ablation needle manipulation. This article introduces two essential maneuvers, the zigzag moving technique and the alienate maneuver, while also reviewing the latest ultrasound techniques in thyroid ablation, contributing valuable insights into this evolving field.

Percutaneous Microwave Ablation for Treatment of Retroperitoneal Tumors.

Purpose To determine if microwave ablation (MWA) of retroperitoneal tumors can safely provide high rates of local tumor control. Materials and Methods This retrospective study included 19 patients (median age, 65 years [range = 46-78 years]; 13 [68.4%] men and six [31.6%] women) with 29 retroperitoneal tumors treated over 22 MWA procedures. Hydrodissection (0.9% saline with 2% iohexol) was injected in 17 of 22 (77.3%) procedures to protect nontarget anatomy. The primary outcomes evaluated were local tumor progression (LTP) and complication rates. Oncologic outcomes, including overall survival (OS), progression-free survival (PFS), and treatment-free interval (TFI), were examined as secondary outcome measures. Results Median follow-up was 18 months (range = 0.5-113). Hydrodissection was successful in displacing nontarget anatomy in 16 of 17 (94.1%) procedures. The LTP rate was 3.4% (one of 29; 95% CI: 0.1, 17.8) per tumor and 5.3% (one of 19; 95% CI: 0.1, 26.0) per patient. The overall complication rate per patient was 15.8% (three of 19), including two minor complications and one major complication. The OS rate at 1, 2, and 3 years was 81.8%, 81.8%, and 72.7%, respectively, with a median OS estimated at greater than 7 years. There was no evidence of a difference in OS (P = .34) and PFS (P = .56) between patients with renal cell carcinoma (six of 19 [31.6%]) versus other tumors (13 of 19 [68.4%]) and patients treated with no evidence of disease (15 of 22 [68.2%]) versus patients with residual tumors (seven of 22 [31.8%]). Median TFI was 18 months (range = 0.5-108). Conclusion Treatment of retroperitoneal tumors with MWA combined with hydrodissection provided high rates of local control, prolonged systemic therapy-free intervals, and few serious complications. Keywords: Ablation Techniques (ie, Radiofrequency, Thermal, Chemical), Retroperitoneum, Microwave Ablation, Hydrodissection © RSNA, 2024.

Comparison of Micro-flow Imaging and Contrast-Enhanced Ultrasound in Ultrasound-Guided Microwave Ablation of Benign Thyroid Nodules.

OBJECTIVE: The study described here was aimed at ascertaining the utility of micro-flow imaging (MFI) during ultrasound (US)-guided microwave ablation (MWA) of thyroid nodules by contrasting its effectiveness with that of contrast-enhanced ultrasound (CEUS). METHODS: Seventy-three patients with eighty-eight thyroid nodules who underwent US-guided MWA were included in our study from January 2020 to June 2023. Thirty-five patients underwent CEUS during the MWA process, and thirty-eight patients underwent MFI during the MWA process. We compared the two groups' baseline characteristics, tumor volume (V), volume reduction rate (VRR), complications and clinical characteristics. RESULTS: Both groups exhibited similar outcomes with respect to V and VRR at 1, 3, 6, 12 and 18 mo after MWA (p > 0.05). Consistency was observed with respect to post-operative complications, supplementary ablation times and surgical duration (p > 0.05). It is worth noting that the MFI group had lower treatment costs compared with the CEUS group (11,337.64 ± 80.93 yuan for the MFI group versus 12,971.23 ± 254.89 yuan for the CEUS group, p < 0.05). CONCLUSION: In the MWA procedure for thyroid nodules, MFI is similar to CEUS with respect to safety and efficacy. Simultaneously, it offers the advantage of reducing surgical expenses, which lessens the economic burden for patients.

Focal Minimally Invasive Treatment in Localized Prostate Cancer: Comprehensive Review of Different Possible Strategies.

BACKGROUND: Focal therapy is a promising, minimally invasive method for the treatment of patients with localized prostate cancer. According to the existing literature, there is growing evidence for positive functional outcomes and oncological effectiveness. The aim of this review is to evaluate the technical efficacy of three minimally invasive techniques (cryoablation, electroporation, and microwave ablation) and their impact on quality of life in patients with prostate cancer. METHODS: Studies between January 2020 and July 2023 were selected using PubMed, Embase, and The Cochrane Library and analyzed following PRISMA guidelines; they have not been registered. RESULTS: Twenty-three studies investigating three different sources of energy to deliver focal therapy were found. Thirteen studies evaluated the performance of the cryoablation therapy, seven studies of the irreversible electroporation, and three studies of microwave ablation option. The majority of studies were retrospective cohort studies. Cryoablation showed excellent oncological outcomes for low-grade prostate cancer, whether performed on the lesion, on the hemigland, or on the entire gland, with the best results obtained for patients with intermediate risk. Irreversible electroporation showed promising oncological outcomes with no significant changes in functional outcomes. Microwave ablation showed great early functional outcomes. CONCLUSIONS: The oncological effectiveness of minimally invasive treatment in comparison to standard of care is still under investigation, despite encouraging results in terms of functional outcomes improvement and adverse events reduction. More comprehensive research is needed to fully understand the function of minimally invasive treatment in patients with localized PCa.

Bipolar ablation involving coronary venous system for refractory left ventricular summit arrhythmias.

Background: Catheter ablation of premature ventricular complexes (PVCs) and ventricular tachycardia (VT) from the left ventricular summit (LVS) may require advanced ablation techniques. Bipolar ablation from the coronary veins and adjacent endocardial structures can be effective for refractory LVS arrhythmias. Objective: The aim of this study was to investigate the outcomes of bipolar ablation performed between the coronary venous system and adjacent endocardial left ventricular outflow tract (LVOT) or right ventricular outflow tract (RVOT). Methods: This multicenter study included consecutive patients with LVS PVC/VT who underwent bipolar ablation between the anterior interventricular vein (AIV) or great cardiac vein (GCV) and the endocardial LVOT/RVOT after failed unipolar ablation. Ablation was started with powers of 10-20 W and uptitrated to achieve an impedance drop of at least 10%. Angiography was performed in all cases to confirm a safe distance (>5 mm) of the catheter from the major coronary arteries. Results: Between 2013 and 2023, bipolar radiofrequency ablation between the AIV/GCV and the adjacent LVOT/RVOT was attempted in 20 patients (4 female; age 57 ± 16 years). Unipolar ablation from sites of early activation (AIV/GCV, LVOT, aortic cusps, RVOT) failed to effectively suppress the PVC/VT in all subjects. Bipolar ablation was delivered with a maximum power of 30 ± 8 W and total duration of 238 ± 217 s and led to acute PVC/VT elimination in all patients. No procedural-related complications occurred. Over a follow-up period of 30 ± 24 months, the freedom from arrhythmia recurrence was 85% (1 recurrence in the VT group and 2 in the PVC group). PVC burden was reduced from 22% ± 10% to 4% ± 8% (P <.001). Conclusion: In cases of LVS PVC/VT refractory to unipolar ablation, bipolar ablation between the coronary venous system and adjacent endocardial LVOT/RVOT is safe and effective if careful titration of power and intraprocedural angiography are performed to ensure a safe distance from the coronary arteries.

Ablative margin quantification using deformable versus rigid image registration in colorectal liver metastasis thermal ablation: a retrospective single-center study.

PURPOSE: To investigate the correlation of minimal ablative margin (MAM) quantification using biomechanical deformable (DIR) versus intensity-based rigid image registration (RIR) with local outcomes following colorectal liver metastasis (CLM) thermal ablation. METHODS: This retrospective single-institution study included consecutive patients undergoing thermal ablation between May 2016 and October 2021. Patients who did not have intraprocedural pre- and post-ablation contrast-enhanced CT images for MAM quantification or follow-up period less than 1 year without residual tumor or local tumor progression (LTP) were excluded. DIR and RIR methods were used to quantify the MAM. The registration accuracy was compared using Dice similarity coefficient (DSC). Area under the receiver operating characteristic curve (AUC) was used to test MAM in predicting local tumor outcomes. RESULTS: A total of 72 patients (mean age 57; 44 men) with 139 tumors (mean diameter 1.5 cm ± 0.8 (SD)) were included. During a median follow-up of 29.4 months, there was one residual unablated tumor and the LTP rate was 17% (24/138). The ranges of DSC were 0.96-0.98 and 0.67-0.98 for DIR and RIR, respectively (p < 0.001). When using DIR, 27 (19%) tumors were partially or totally registered outside the liver, compared to 46 (33%) with RIR. Using DIR versus RIR, the corresponding median MAM was 4.7 mm versus 4.0 mm, respectively (p = 0.5). The AUC in predicting residual tumor and 1-year LTP for DIR versus RIR was 0.89 versus 0.72, respectively (p < 0.001). CONCLUSION: Ablative margin quantified on intra-procedural CT imaging using DIR method outperformed RIR for predicting local outcomes of CLM thermal ablation. CLINICAL RELEVANCE STATEMENT: The study supports the role of biomechanical deformable image registration as the preferred image registration method over rigid image registration for quantifying minimal ablative margins using intraprocedural contrast-enhanced CT images. KEY POINTS: • Accurate and reproducible image registration is a prerequisite for clinical application of image-based ablation confirmation methods. • When compared to intensity-based rigid image registration, biomechanical deformable image registration for minimal ablative margin quantification was more accurate for liver registration using intraprocedural contrast-enhanced CT images. • Biomechanical deformable image registration outperformed intensity-based rigid image registration for predicting local tumor outcomes following colorectal liver metastasis thermal ablation.

Incidence and clinical impact of bile ducts changes after multibipolar radiofrequency ablation for hepatocellular carcinoma.

OBJECTIVES: This study aimed to evaluate the incidence and clinical implications of bile duct changes following multibipolar radiofrequency ablation (mbpRFA) for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Radiological, clinical, and biological data from consecutive cirrhotic patients who underwent first-line mbpRFA between 2007 and 2014 for uninodular HCC ≤ 5 cm were retrospectively collected. Follow-up imaging was reviewed to identify bile duct changes and factors associated with biliary changes were assessed using multivariable analysis. Baseline and 6-month liver function tests were compared in patients with and without bile duct changes. Complications, cirrhosis decompensation, and survival rates were compared in both groups. RESULTS: A total of 231 patients (mean age 68 years [39-85], 187 men) underwent 266 mbpRFA sessions for uninodular HCC (mean size 26 mm). Of these, 76 (33%) developed bile duct changes (upstream bile duct dilatations and/or bilomas) with a mean onset time of 3 months. Identified risk factors for these changes were the infiltrative aspect of the tumor (p = 0.035) and its location in segment VIII (p < 0.01). The average increase in bilirubin at 6 months was higher in the group with biliary changes (+2.9 vs. +0.4 µg/mL; p = 0.03). There were no significant differences in terms of complications, cirrhosis decompensation at 1 year (p = 0.95), local and distant tumor progression (p = 0.91 and 0.14 respectively), and overall survival (p = 0.4) between the two groups. CONCLUSION: Bile duct changes are common after mbpRFA for HCC, especially in tumors with an infiltrative aspect or those located in segment VIII. These changes do not appear to negatively impact the course of cirrhosis at 1 year or overall survival. CLINICAL RELEVANCE STATEMENT: Bile duct changes following mbpRFA for HCC are relatively common. Nevertheless, they do not raise clinical concerns in terms of complications, deterioration in liver function, or survival rates. Consequently, specific monitoring or interventions for these bile duct changes are not warranted. KEY POINTS: • Bile duct changes are frequently observed after multibipolar radiofrequency ablation for hepatocellular carcinoma, occurring in 33% of cases in our study. • Patients with bile duct changes exhibited a higher increase in bilirubin levels at 6 months but no more cirrhosis decompensation or liver abscesses. • Biliary changes following multibipolar radiofrequency ablation for hepatocellular carcinoma are not alarming and do not necessitate any specific monitoring or intervention.